Horton

Re: PG 15 (and to a smaller degree 14) regression due to ExprEvalStep size

Amit Langote <amitlangote09@gmail.com>

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From: Amit Langote <amitlangote09@gmail.com>
To: Andrew Dunstan <andrew@dunslane.net>
Cc: Andres Freund <andres@anarazel.de>, Michael Paquier <michael@paquier.xyz>, John Naylor <john.naylor@enterprisedb.com>, "Jonathan S. Katz" <jkatz@postgresql.org>, Tom Lane <tgl@sss.pgh.pa.us>, David Rowley <dgrowleyml@gmail.com>, Peter Geoghegan <pg@bowt.ie>, PostgreSQL-development <pgsql-hackers@postgresql.org>, Nikita Glukhov <n.gluhov@postgrespro.ru>
Date: 2022-07-19T11:40:11Z
Lists: pgsql-hackers

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Hi,

On Tue, Jul 19, 2022 at 4:09 AM Andrew Dunstan <andrew@dunslane.net> wrote:
> On 2022-07-15 Fr 17:07, Andres Freund wrote:
> > Perhaps you could post your current state? I might be able to help resolving
> > some of the problems.
>
> Ok. Here is the state of things. This has proved to be rather more
> intractable than I expected. Almost all the legwork here has been done
> by Amit Langote, for which he deserves both my thanks and considerable
> credit, but I take responsibility for it.
>
> I just discovered today that this scheme is failing under
> "force_parallel_mode = regress". I have as yet no idea if that can be
> fixed simply or not.

The errors Andrew mentions here had to do with a bug of the new
coercion evaluation logic.  The old code in ExecEvalJsonExpr() would
skip coercion evaluation and thus also the sub-transaction associated
with it for some JsonExprs that the new code would not and that didn't
sit well with the invariant that a parallel worker shouldn't try to
start a sub-transaction.

That bug has been fixed in the attached updated version.

> Apart from that I think the main outstanding issue
> is to fill in the gaps in llvm_compile_expr().

About that, I was wondering if the blocks in llvm_compile_expr() need
to be hand-coded to match what's added in ExecInterpExpr() or if I've
missed some tool that can be used instead?

-- 
Thanks, Amit Langote
EDB: http://www.enterprisedb.com

Commits

  1. JSON_TABLE: Add support for NESTED paths and columns

  2. Add basic JSON_TABLE() functionality

  3. Add SQL/JSON query functions

  4. Add soft error handling to some expression nodes

  5. Adjust populate_record_field() to handle errors softly

  6. Refactor code used by jsonpath executor to fetch variables

  7. Add more SQL/JSON constructor functions

  8. SQL/JSON: support the IS JSON predicate

  9. SQL/JSON: add standard JSON constructor functions

  10. Add static assertion ensuring sizeof(ExprEvalStep) <= 64 bytes

  11. Remove size increase in ExprEvalStep caused by hashed saops

  12. pgstat: reduce timer overhead by leaving timer running.

  13. expression eval: Fix EEOP_JSON_CONSTRUCTOR and EEOP_JSONEXPR size.

  14. SQL/JSON query functions

  15. Speedup ScalarArrayOpExpr evaluation